Airbag and airbag systems have been used for years. In fact, these systems are now mandatory on new vehicles. These systems have been credited with saving literally thousands of lives and dramatically increasing automotive safety.
One type of airbag system that has received recent attention is the so-called “inflatable curtain” airbag. (These airbags are also referred to as “inflatable cushion” airbags as well). These airbags are positioned proximate the vehicle's door or side and are designed to inflate in the event of an accident. When this type of airbag is inflated, it will cover the door and lateral side of the vehicle, thereby preventing the vehicle occupant from harmful impact with the door or side of the vehicle during a crash. Such inflatable curtain airbag systems may also ensure that the all or a portion of the occupant's body is not ejected out of the vehicle during a crash. Accordingly, because of the added safety associated with inflatable curtain airbags, these types of airbag systems have also become standard on many new vehicles.
Oftentimes, inflatable curtain airbags are positioned in the vehicle's roof rail proximate the vehicle door. Such airbags, when inflated, will be lowered down from the vehicle's roof and are positioned between the vehicle occupant and the vehicle door. However, such a design is not possible for certain makes/models of cars. Accordingly, for these types of vehicles, inflatable curtain airbag systems have been mounted within the vehicle door. This type of airbag is often referred to as a “door mounted inflatable curtain” or a “DMIC”.
Currently, DMICs are designed such that the length of the DMIC airbag is greater than the length of the space into which they are inserted onto the vehicle door. Accordingly, in order to position the DMIC, the DMIC must be folded. FIGS. 1A through 1C show this folding process in greater detail. Specifically, FIG. 1A shows the unfolded DMIC airbag 2. The airbag 2 includes a leading edge 3a, a rear edge 3b, a top edge 3c, and a bottom edge 3d. As shown in FIG. 1B, a triangular portion 4 of the airbag 2 is folded over (along fold 5) to reduce the length 6 of the airbag 2. Accordingly, the rear edge 3b is positioned on the interior of the airbag 2. Once the length 6 has been reduced, the airbag 2 will have a length small enough to fit into the area of the vehicle door designated to receive the airbag 2. It should be noted that when the triangular portion 4 is folded over, the airbag 2 has an overall trapezoidal shape (see FIG. 1B). After the length 6 has been reduced, the airbag 2 may be further compacted by having the top edge 3c be folded towards the bottom edge 3d via folds 7.
FIG. 2 shows the airbag 2 mounted onto a vehicle door 10. In FIG. 2, the airbag 2 is shown as it is being inflated. As known in the industry, the inflated airbag 2 may have one or more seams 9, as desired. For purposes of clarity, a plane 12 is shown on FIG. 2 to indicate the folded over portion 4—i.e., the portion of the airbag 2 that must be folded over in order to reduce the length of the airbag 2 so that the airbag 2 can fit into the area of the door 10 designed to receive this feature. When inflated, the airbag 2 becomes positioned in the vehicle interior 20 in a position that will prevent the occupant from harmful impact with the door 10, the window (not shown), the lateral side, and/or other portions of the vehicle interior 20.
Referring now to FIGS. 1A-1C and FIG. 2, it will be noted that the position of the DMIC airbag 2 may be such that it is positioned as far to the rear of the door 10 as possible. This is needed to minimize the size of the folded over portion 4. The packing length of the compacted (folded) airbag 2 should be kept as long as possible in order to avoid, if possible, the need for a similar type of folded over portion 4 proximate the leading edge 3a of the airbag 2. Typical coverage area for the DMIC airbag 2 is between 550 to 650 square millimeters depending upon the particular embodiment. The area of the folded over portion 4 may be between 150 and 200 square millimeters. Of course, an inflator (not shown) would be used to inflate the airbag 2. The type, size, and features of the inflator that would be used will depend upon the particular embodiment and are well known to those skilled in the art. The exact position of the inflator on the vehicle could vary depending upon the design of the vehicle. Particularly, the position of the inflator may be modified, as needed, to ensure that the inflator does not contact a dummy thorax (or other portions of the crash test dummy) during testing.
It should be noted that the use of a folded over portion 4 may be undesirable in certain applications. For example, the folded over portion 4 means that there is a fold 5 that is parallel to the compacted length 11. This compacted length 11 must be first unfolded (uncompacted) before the portion 4 may be unfolded along the fold 5. Such a configuration increases the complexity of the system and may also increase the time required for the airbag 2 to properly inflate into position. Accordingly, a larger or stronger inflator may be required in order to ensure that the airbag 2 deploys within the desired time. Further, the folded over portion 4 may also cause issues with respect to the kinematics of deployment. Accordingly, engineers and testers are required to configure the airbag 2 to ensure that the airbag 2 will deploy properly.
Accordingly, it would be an advancement to find a new way of folding a DMIC airbag that would not create a folded over portion. Such a method is taught herein.